The present invention pertains to a device for advancing workpieces to and orienting the same in a position adjacent to the sewing zone in a sewing unit. In such sewing units, the workpieces are either fed continuously by an operator or by a mechanical feeder so that they become oriented in such a manner so as to be positioned in the sewing zone parallel to the feed line of the sewing machine that forms a part of said sewing unit.
Devices for advancing to and orienting workpieces in the sewing zone and in the line of feed of the unit's sewing machine by means of transmission belts are well known to those conversant in the art. Such known devices, however, have not been entirely satisfactory in the performance of their intended function for the workpieces are frequently subjected to uncontrolled displacement on the transmission belts. To correct the problem of workpiece displacement with devices of the prior art, inclined wheels or rollers provided with a helicoidal portion have been tried in combination with the transmission belts. This combination has been effective in applying a thrust in the direction of a vehicle guide wall which extends parallel to the feed line of the sewing machine. Certain patents show and describe prior art devices of the above type and for a more detailed description thereof, attention is directed to U.S. Pat. No. 3,903,820 and German Pat. No. 2,451,229.
The attempts to correct the problems of the prior art devices have not been completely satisfactory for the combinations of the wheels as rollers with the transmission belts has at times been ineffective and what is considered to be too slow since the alignment is accomplished by steps and depends on the initial position in which the workpiece is brought into engagement with the wheels and rollers. If this position is too great a distance from the ideal alignment, the workpiece will arrive at the sewing zone before it is correctly oriented resulting in sewing not being formed along the edge thereof as desired.
Another form of prior art device which utilizes two series of transmission belts disposed at right angles to one another is shown and described in German Pat. No. 1,949,525. Although this device performs its intended function satisfactorily, it is considered to be of excessive size and complexity.
The workpiece positioner for sewing units comprising the invention has overcome the troublesome and undesirable conditions described above by providing a device that accurately and continuously positions a workpiece in the most desirable location for forming a seam of stitches thereon.